FPGA signal processing for radar / sonar applications

R and sonar applications are signalprocessing intensive and heavily rely on the efficient implementation of such digital signal-processing (DSP) algorithms as filtering, transforms and modulation. In past systems, conventional digital signal processors were used to perform many of these algorithms. However, field-programmable gate arrays (FPGAs) deliver an order of magnitude higher performance than traditional DSPs. A key reason is that an FPGA can side step the classic Von Neumann architecture’s instruction—fetch, load/store bottleneck—found in most DSPs. Another reason is the FPGA’s lower power consumption. When approaching the problem of implementing signal-processing functions within an FPGA, designers have developed the mindset that these functions must be optimally coded from the ground up for their application or significantly modified. However, siliconoptimized, high-precision math functions are being developed for specific applications as part of the programmable logic product offering of many vendors, including Altera, making complex systems easier to manage and lower risk. Changing requirements in radar applications Modern military radar systems have evolving requirements, both in how the systems are designed and how the end user uses the data. This results in some of the same design changes in electronic systems affecting both the military and commercial design communities. That is, the need for smaller, energy-efficient systems with high processing-power requirements. This makes low power consumption a key driver in most designs. With warfare having become more urban, ground clutter and background noise take on additional significance for the radar operator, thus demanding more processing power and better algorithms. Overlaying data from multiple sensors and known terrain features is one approach to increasing resolution, but this too has impacts on system-processing requirements and user-decision models. High-speed digital systems make new digital beam-forming technologies possible, increasing the number of beams and nulls available for warfighting and surveillance missions. More digital logic also allows designers to make early decisions on actionable intelligence and to meta-tag sensor data earlier for more efficient analysis. These and other emerging techniques will allow for the creation of better radar or sonar systems, but each requires additional signal-processing resources. One of these resources is the emerging class of high-performance FPGAs. One of the primary differences in the past between FPGAs and application-specific integrated circuits (ASICs) has been greater complexity in the latter class of devices. However, with the 65 nm generation of FPGAs, and 45 nm devices on the horizon, FPGAs in sensor systems have become nearly as complex as ASICs. This complexity comes from rapidly increasing logic density, as well as from the integration of the many different processing functions now integrated into one device.